1. Field of the Invention
The present invention relates to an audio processing apparatus and a video processing apparatus capable of communicating delay information about video display to control delay time of audio signal, and also relates to a method for controlling these apparatuses.
2. Description of the Related Art
The technology has been conventionally known that eliminates a time lag between video to be displayed and audio to be output and reproduces the synchronized video and audio in a video/audio player. Japanese Patent Application Laid-Open No. 2002-344898 discusses the following method for synchronizing video and audio. A video processing apparatus monitor sends delay time information, as a control command, caused by an intrinsic delay factor for video display to an amplifier via a serial bus. The amplifier provides a required delay time to synchronize an audio output with a video display according to the control command.
According to the method for synchronizing video and audio discussed in Japanese Patent Application Laid-Open No. 2002-344898, a time lag between video and audio is set according to the intrinsic delay factor of processing carried out in the monitor. Therefore, in a case, for example, where the image processing method changes depending on the type of an input device, sufficient synchronization is difficult to obtain.
The image processing time changes depending on the type of input video signal, such as a still image/moving image and resolution, the type of an input device, such as a game console or a digital versatile disc (DVD) player, and an image quality setting by the user. If the delay time for video display changes due to a change in image processing time, synchronization of video and audio may become insufficient when they are reproduced.